Coil assembly with variable premagnetization



1954 P. J. H. JANSSEN COIL ASSEMBLY WITH VARIABLE PREMAGNETIZATION Filed March 11, 1952 "a x; vw a.) 1 W 0 0 0 up 0 0 6 0 3 0 m .0 0... 3 0 0 z. 00. 0.6% v3 .0

INVENTOR Junssn a I Agent Patented Oct. 12 1954 COIL ASSEMBLY WITH VARIABLE PREMAGNETIZATION Peter Johannes Hubertus Janssen, Eindhoven, Netherlands, assignor to Hartford National Bank and Trust Company, Hartford, Conn, as

FFiQE.

trustee Application March 11, 1952, Serial No. 275,921

Claims priority, application Netherlands April 5, 1951 4 Claims.

This invention relates to a coil assembly with variable premagnetization.

The main object of the invention is to provide a magnetic coil having a ferromagnetic core and means for providing smooth and accurate control of the premagnetization of the core.

This and other objects of the invention will be best understood from the following description.

According to the invention, the coil assembly main core.

can be accurately adjusted.

magnetization of the core.

tion;

magnet and the core.

a synthetic resin.

2 to a center axis of the support 9 and substantially parallel thereto and to the core 3. A slot 15 is provided on one of the end faces of the support H so that it may be rotated by means of a screw driver.

The magnetic field produced by the permanent magnet is is partly closed through the ferromagnetic core 3, resulting in premagnetization of the core 3. The intensity of the premagnetization naturally varies with the spacing between 10 includes a premanent magnet spaced from the the core 3 and the permanent bar magnet i3. It Both the core and the magnet are is obvious that rotating the cylindrical support adapted to be moved relative to each other to II about its longitudinal axis causes the said vary the spacing therebetween. With such an spacing to vary and thus enables the premagneth arrangement, the premagnetization of the core zation of the core 3 to be varied.

In the position in which the core 3 and the In a preferred embodiment, a rod-like magnet magnet bar l3 are closest to one another (diais arranged parallel to the ferromagnetic core grammatically shown in Fig. 3) the magnetizaof a coil winding and is secured to a cylindrical tion is a maximum, in which case, the core 3 support of non-magnetic material adapted to 29 will generally be saturated. In this position, a rotate about its longitudinal axis thereby alteriv n v ri ti n in pa between h c re an ing the spacing between the magnet and the ferthe magnet is found to have a greater effect on romagnetic core and, consequently, the degree of the resultant magnetization of the core than in the positions in which the spacing is larger. The invention will now be described with refother words, the sensitivity of control for differerence to the accompanying drawing in which: cut spacing between the core and the magnet is Fig. 1 is a view, in cross-section, of one form not Constant However, as shown in of magnetic coil in accordance with th in this difference in sensitivity is compensated for by the circular movement of the magnet IS. in Fig. 2 is an end view of the coil shown in Fig. 1; this figure, a, b, and c designate three positions Fig. 3 is a diagrammatic representation of the 30 Which the magnet l3 o p s in relat on to coil shown in Fig. 1 showing how a smooth cone Core 3 e t pp N F ot sh wn trol of premagnetization of the core is obtained; in Fig. 3) is turned twice in succession through Figs. 4 and 5 are simplified views of the coil the Same angle- AS y e Seen o the figshown in Fig. 1 illustrating the need for mainures, the Variation in distance ab' which retaining the parallel relationship between the Sults from the fi angular rot tion is much smaller than the variation bc due to the second Referring to Figs. 1 and 2, the coil assembly rotation. Consequently, a substantially constant comprises a winding i and a rod-like ferromag- Sensitivity of Control hence, a Smooth C011- netic core 3 which may consist of cubic mixed trol is thus obtained. crystal ferrite, of the type described in U. s. to F 4 and 5 demonstrate e p rtance of Patents 2,452,529, 2,452,530 and 2,452,531 to J. L. the opposed p h p n of the core 3 and Shock issued. The winding 5 with its core 3 is agnet rod l3. Fig. 4 Shows hat in t parallel secured in position in a suitable cylindrical bore position the lines of force which emanate from 5 in a housing 1 of non-magnetic t l, g., H the magnet it will enter the core 3 primarily at the ends of the core outside the wound part or A second cylindrical bore 9, adjacent to and coil I. The magnetization is, consequently, subabove the bore 5, extends lengthwise through n i lly on tant i the W n p f th the housing i and is parallel to the bore 5. A core. If, however, as shown in Fig. 5, the rod cylindrical support ll of non-magnetic material, I3 is inclined relative to the core 3, part of the e. g., synthetic resin, is journalled in the bore 9 flux will, as shown in the figures, enter the core and is adapted to be rotated within said bore through the winding 1 adjacent those ends of about its longitudinal axis. A rod-like permathe core and magnet which are remote from nent magnet I3 is secured to the support II in each other (at the right of Fig. 5), because at a manner such that it is eccentric with respect this point the distance is less than at the in- 3 volved ends themselves. This results in the wound part of the core 3, which is furthest to the right, being. less saturated than the remaining part, and that the part of thecoil which corresponds to the said part has an induction different from that of the saturated part. This constitutes a disadvantage which can be obviated by a permanently substantially opposed parallel position of the core and the magnet.

In view of the above, it is also important that the magnet I3 not be excessively, short. compared with the coil l since with an excessively, short magnet, lines of force will again pass laterally through the Winding, and as explained before, this is undesirable. In practice, it issatisfactory if the rod is longer or at least not shorter than.

the wound part of the core and that these two elements are directly opposite one another.

While the invention has been described in connection with specific examples and in specific application, other modifications thereof will be readily apparent to those skilled in the art without departing from the invention as. defined in the appended claims.

What I claim is:

1. A coil assembly comprising a housing of non-magnetic material, a coil within said housing, a rod-like core of ferromagnetic material within said coil, a cylindrical member of nonmagnetic material. rotatably supported Within the housing, and a permanent magnet eccentrically secured to said cylindrical member and. extending opposedly parallel to and spaced from said core for varying the spacing between the core and the permanent magnet to thereby alter the premagnetization of said core upon rotation of said cylindrical member.

2. A coil assembly comprising a housing of non-magnetic material, a coil within said housing, a rod-like core of ferromagnetic material 40 within said coil, a cylindrical member of nonmagnetic material arranged parallel to said core within said housing, and a permanent magnet secured to said cylindrical. member and arranged parallel to the axis of the cylindrical member for varying the spacing between the core and the permanent magnet to thereby alter the premagnetization of said core upon rotation of said cylindrical member.

3. A. coil assembly comprising a housing of non-magnetic material, a coil within a portion of said housing, a rod-like core of ferromagnetic material within said coil, a cylindrical member of non-magnetic material journalled within a second portion of said housing and parallel to said coil, and a permanent magnet supported by and arranged parallel to the axis of said cylindrical member for varying the spacing between the core and the permanent magnet to thereby alter the premagnetization of said core upon rotation of said cylindrical member.

4'. A call assembly comprising a housing of non-magnetic material, a coil within said. housing, a rod-like core.- of ferromagnetic material having a given length within said coil, acylindrical member oi non-magnetic material journalled in said housing, and a permanent magnet having a length at least equal to said given core length supported by and arranged parallel to the axis of said cylindrical member for varying the; spacing between thecore and the permanent magnet to thereby alter the premagnetization of 'said core upon rotation of said cylindrical member.

References Cited in the file of this patent UNITED STATES. PATENTS Number Name Date 1,896,510 Given Feb. 7, 1933 2,000,378" Deisch May 7', 1935 2,503,155 Harvey et. al. Apr. 4', 1950 

